1. Field of the Invention
The present invention relates in general to transducers, and more particularly to acoustic transducers. The present invention also relates to a hybrid form of a transducer preferably a unitary piezoelectric magnetostrictive transducer.
2. Background Discussion
A hybrid transducer construction is shown in my earlier granted U.S. Pat. No. 4,443,731. This transducer construction employs both a magnetostrictive and a piezoelectric section constructed of different magnetostrictive and piezoelectric materials. In at least one embodiment of the invention as described in this earlier patent, the magnetostrictive and piezoelectric segments are intercoupled in series allowing cancellation of motion at one end of the transducer and maximization of the motion at the other end thereof. In essence, such a transducer provides a large front to back ratio for motion at its two ends. With a large radiating surface or in an array environment, a directional beam of sound is obtained.
As described in this prior patent, the different piezoelectric and magnetostrictive segments are constructed to produce a generally linear transducer that is in a bar or rod construction. In this patent the device is described a one in which the total length is equal to one half wavelength of sound with each section being one quarter wavelength in length in the respective materials. This allows the waves from either section to arrive in proper phase at the opposite ends and add at one end while cancelling at the other end. This device is thus in particular useful as a unidirectional transducer.
It is a general object of the present invention to provide a hybrid transducer that is generally of the type described in this prior art patent but which is of improved construction.
Another object of the present invention is to provide a hybrid transducer in accordance with the preceding object and which employs mass and also preferably compliance loading which in particular permits operation at a lower frequency.
Still another object of the present invention is to provide an improved unidirectional hybrid transducer which is in particular adapted for use with a piston or mass construction to provide efficient use thereof for coupling energy to the medium.
A further object of the present invention is to provide a unidirectional hybrid transducer that can be constructed in a ring configuration.